Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/02—Well-drilling compositions
  • C09K8/04—Aqueous well-drilling compositions
  • C09K8/14—Clay-containing compositions
  • C09K8/18—Clay-containing compositions characterised by the organic compounds
  • C09K8/22—Synthetic organic compounds
  • C09K8/24—Polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/02—Well-drilling compositions
  • C09K8/04—Aqueous well-drilling compositions
  • C09K8/14—Clay-containing compositions
  • C09K8/145—Clay-containing compositions characterised by the composition of the clay
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S507/00—Earth boring, well treating, and oil field chemistry
  • Y10S507/901—Organically modified inorganic solid

Definitions

• the present invention relates to pre-treated clays, their preparation, and their use in formulating dri lling muds which are not aggressive to layer clays.
• water-based fluids which contain clays, in particular bentonite, and various kinds of additives, among which the necessary dispersants in order to obtain the desi red Theological properties.
• these water-based muds display the advantage of a Lower cost and lower polluting capabi lity; unfortunately, they display the drawback of being aggressive to the clay layers met during the borehole dri lling and to the clay scraps generated during the course of the same dri lling.
• the aggressivity is partially due to the dispersants, generally of polymeric type, added to the mud in order to favour the dispersion of bentonitic clay and endow the mud with suitable fluidity.
• the polymeric dispersant is only partially adsorbed on bentonite, that portion of dispersant which remains free in solution can thus act also on layer clay and on the clay contained in the dri lling scrap material, increasing the above problems .
• GB-A-2,216,574 teaches the addition of a polyglycerol to the dri lling mud, as a solution to the problem.
• EP-A-333,458 discloses mixtures of water-soluble, high-molecular-weight additives capable of forming strong enough nucleophi lic sites when treated with bases and one or more potassium salts having a high enough alkalinity to increase the pH value of the dri lling mud up to a higher value than 9.
• US-A-3,953,336 claims the use of water based muds containing a cellulose derivative.
• the present invention relates to a process for preparing aqueous clay-based dri lling muds which are not aggressive to layer clays, which process comprises:
• the clay used in order to prepare the mud is bentonite.
• the most commonly used dispersants in order to fluidify benton i t e-based muds are I i gnosu Lfonates , lignites, po I yac ry L ates and partially hydrolysed po lyacry lami des .
• the dispersants are po lyac ry Lates or thei r copolymers, sti ll more preferably polyacrylates.
• the necessary dispersant amount in order to fluidify said muds depends on the chemical nature of the same dispersant, and on the type of bentonite.
• ligninic dispersant When ligninic dispersant are used, such an amount is generally comprised within the range of from 0.5 to
• the clay may be suspended in water and the dispersant added, or, indifferently, the aqueous solution of dispersant may be added to pristine clay.
• the aqueous dispersion of bentonite and the dispersant are mixed for a time period which is at Least Long enough in order to obtain the adsorbtion of the dispersant; said time period generally is of the order of approximately 30 minutes.
• a portion of the dispersant is adsorbed on clay surface, with the balance remaining in the solution.
• the amount adsorbed on clay surface is the amount which corresponds to the solid- dispersant equi librium. For dispersants of polyacrylic type, this amount is of approximately one third of the total amount added in order to fluidify the mud.
• the temperature at which the clay is equi librated with the dispersant is not determinati e; preferably, the process is carried out at a temperature comprised within the range of from 10 to 40°C.
• the pre-treated cLay i .e., the clay with its surface coated with dispersant additive, is then recovered.
• Said clay can be separated from the aqueous solution according to well-known techniques of liquid- solid separation, preferably by cent ri fugat i on .
• This clay recovery step can be followed by one or more washing steps with water, so as to completely remove any dispersant which is not strongly bonded to clay.
• the so treated clay is then re-dispersed in water, and the resulting mud is used as a borehole dri lling fluid, particuLarly suitable for dri lling oi l wells having temperatures of approximately 120-170°C.
• the resulting dri lling mud can be admixed with other additives as usually employed in the end formulation. So, for example, thickening agents, fluid-Loss agents, fi ltrate control agents, and so forth, can be added.
• water-so lub Le salts can be added in order to regulate the ionic strength, as well as suitable substances for adjusting the pH value of the same mud at the desired value.
• the pH value of the so formulated mud is comprised within the range of from 9 to 12.
• the re-dispersion in water of the so treated bentonite does not cause the removal of the adsorbed dispersant (at least under customary dri lling mud use time and temperature conditions). This means that said adsorbed dispersant wi ll continue to perform its task as bentonite dispersant also in the absence of other dispersants in solution.
• the so prepared mud by being practically free from water dissolved dispersant, demonstrates to be Less aggressive to Layer clays and the overall process requires a lower consumption of dispersant additive, because the not adsorbed amount contained in the initial aqueous solution can be easi ly recovered and recycled.
• the pre-treated clay according to the present invention can also be stored for long time and used when necessary in order to prepare the dri lling " mud.
• a dispersion of bentonite in water is prepared with a suitable amount of dispersant; the clay dispersion is centrifuged and (1 ) a compact sediment of clay with adsorbed dispersant and (2) a water solution containing non-adsorbed dispersant (supernatant) are obtained.
• the so prepared bentonite (step 1) is the base component for preparing the non-aggressive mud.
• the so prepared dispersion is allowed to equi librate during 16 hours and then is submitted to a
• the initial aqueous dispersion containing 3.7% w/w of Wyoming bentonite is centrifuged for 2 hours at 14,000 rpm, in order to obtain the liquid supernatant "L”; finally, the sediment with dispersant "SD” is redispersed in the supe mat ant "L” .
• a dispersion of pre-treated clay is obtained in which the aqueous phase has salinity and pH values which are approximately the same as of Samp les A and B .
• Iable_2 RheologicaL character stics of the base dispersion (A), of the dispersion admixed with the dispersant (B) and of the dispersion treated according to Scheme
• HRT hot-rolling test
• the test is carried out by adding to the dispersion known amounts of layer clay in granular form, with defined particle size (2-4 mm) .
• the so prepared dispersion is submitted to heat ageing for a 4-hour time at 93°C, inside a container kept rolling at a revolution speed of 17 rpm. Finally, the dispersion is cooled and from it the residue of granular clay is removed.
• Clay reco ⁇ very rate 45% 63% The HRT test carried out on these dispersions confirms that, by removing the excess dispersant from the solution, the aggressivity of the dispersion to layer clay decreases. With Sample B a clay recovery rate of 45% is obtained versus a recovery rate of 63% obtained with Sample C.
• the rheologicaL measurements carried out on the dispersions after the HRT test show that the layer clay, which has partially got dispersed, generally increased the rheologicaL parameters, however without a strong effect on the behaviour. It should be observed that Sample C, by causing a Lower dispersion of Layer clay into the mud, caused lower increases.

Landscapes

• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
• Colloid Chemistry (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Treatment Of Sludge (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)
• Lubricants (AREA)
• Removal Of Floating Material (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11363990

Family Applications (1)

Country Status (13)

Cited By (1)

Families Citing this family (6)

Citations (6)

Family Cites Families (7)

• 1992
  • 1992-09-24 IT ITMI922188A patent/IT1255519B/it active IP Right Grant
• 1993
  • 1993-09-23 DE DE69324026T patent/DE69324026T2/de not_active Expired - Fee Related
  • 1993-09-23 DK DK93920809T patent/DK0662113T3/da active
  • 1993-09-23 CA CA002145090A patent/CA2145090A1/en not_active Abandoned
  • 1993-09-23 AT AT93920809T patent/ATE177777T1/de active
  • 1993-09-23 BR BR9307081A patent/BR9307081A/pt not_active IP Right Cessation
  • 1993-09-23 US US08/397,056 patent/US5646092A/en not_active Expired - Fee Related
  • 1993-09-23 EP EP93920809A patent/EP0662113B1/de not_active Expired - Lifetime
  • 1993-09-23 JP JP6507815A patent/JPH08503494A/ja active Pending
  • 1993-09-23 ES ES93920809T patent/ES2128435T3/es not_active Expired - Lifetime
  • 1993-09-23 WO PCT/EP1993/002586 patent/WO1994006881A1/en active IP Right Grant
  • 1993-09-24 CN CN93119847A patent/CN1042740C/zh not_active Expired - Fee Related
• 1995
  • 1995-03-22 NO NO951092A patent/NO951092L/no not_active Application Discontinuation

Patent Citations (6)

Also Published As

Similar Documents

Legal Events